Structural Materials Commons^™

Numerical Simulation On Bearing Characteristics Of Tunnel‑Type Anchorage Of A Grand Bridge Over Qingjiang River, Yin Hongmei, Shi Qian, Zhang Yihu

Journal of China & Foreign Highway

This paper took the tunnel-type anchorage on the left bank of a grand bridge over the Qingjiang River as an example and established a three-dimensional geological generalization model based on the engineering geological analysis.In addition，the paper used different software to realize the approximate grid discrete division of complex rock mass and tunnel-type anchorage structure.FLAC3D software was used to simulate different working conditions，and the deformation characteristics and bearing capacity of the tunnel-type anchorage were obtained.It is found that the potential failure mode of the tunnel-type anchorage is that the anchor and the rock mass cut by the structural plane on the …

Study On Length Of Deceleration Lane Of Left Off‑Ramp For Urban Underground Interchanges Based On Traffic Conflicts, Wang Hailiang, Cheng Chong, Guan Hong, Ding Naikan

Journal of China & Foreign Highway

To set a reasonable range of the length of the deceleration lane in the diverge area of the left off-ramp for urban underground interchanges，the effects of the length of the deceleration lane，as well as interactions between traffic volumes and design speeds of mainline and ramp on traffic conflict in the diverge area，were exami ned.By taking the underground interchange of the Wuhan East-South Lakes Tunnel Project as an example，the VISSIM micro traffic simulation test was carried out，and the conflict rate （RCR） and exposed time to collision （TTET） were extracted.The results show that ① when the length of the deceleration lane increases，the …

Study On Safety Risk Assessment System For Waste Dump Of Mountainous Expressways, Ye Xian, Yin Hao, Zhao Xin, Wang Guanqun, Gao Yu

Journal of China & Foreign Highway

The safety of waste dump projects of mountainous expressways is related to environmental protection，water and soil conservation，highway building protection，and downstream environment-sensitive point protection，so it is necessary to put forward safety assessment methods.Based on the data analysis of 1 369 waste dumps in Yunnan Province，the safety risk factors of the waste dump engineering were proposed and summarized as five primary indicators，including site selection and design factors，construction factors，regional geological factors，external influencing factors，and data integrity factors，and 18 secondary indicators were further put forward.The group decision-making analytic hierarchy process （AHP ） model was established，and the weight of secondary indexes was determined by 64 technical …

Analysis On Design Concept Of Subgrade And Pavement Of Colombia High‑Grade Highway, Liu Tao, Hu Guanhua, Yuan Yi

Journal of China & Foreign Highway

Colombian highway design predominantly adheres to American Standards，emphasizing design concepts reflective of the United States while encompassing Colombia's engineering design habits，concepts，and characteristics.This paper introduced the main design schemes of the Colombia MAR 2 Highway Project in northern Colombia，including protection engineering，drainage engineering，subgrade filling，spoil ground，and pavement.It conducted a comparative analysis between Colombian and Chinese design concepts，highlighting similarities and disparities，and put forward the thinking of mutual learning.

Study On Flexural Behavior Of Wet Joints Of Prefabricated Steel‑Uhpc Composite Bridge Deck, Liao Wancheng, Zhao Hua, An Jiahe

Journal of China & Foreign Highway

Prefabricated steel-UHPC composite bridge deck is a new deck structure system that places the longitudinal rib at the upper layer and forms PBL shear connectors.This structure can be prefabricated in the factory and assembled on-site.The adjacent steel beams are integrated by welding，and the cast in-situ UHPC wet joints connect the adjacent UHPC bridge decks.However，these wet joints represent the structure's vulnerable segments but with little research.To this end，a full-scale model test has been conducted to study the flexural behavior of the wet joints in a steel-UHPC composite bridge deck in a practical project.The Abaqus finite element model was established and verified …

Research On Shape Optimization Of Four‑Center Circular Highway Tunnel Based On Parametric Modeling Idea, Zhu Lei, Guo Meng, Guo Jinyong, Shen Caihua, Zhang Hanyi

Journal of China & Foreign Highway

The rational cross-sectional form of the four-center circular highway tunnel contributes to enhancing the stress state of the lining structure，reducing cracks in the composite lining，and enhancing the durability of the tunnel structure.Utilizing the Ansys APDL programming platform and guided by the design principle of continuous-curvature，a parametric modeling equation for the geometrical dimensions of local tunnel shape in arch foot area was established.The calculation method and numerical simulation models for the equivalent mechanical parameters of the anchor reinforcement area were also developed.The study revealed the impact of the local tunnel shape parameter design in the arch foot area on the internal …

Thermal Insulation And Fire Protection Plaster For Frp System Incorporating Aerogel Nanoparticles And Phyllosilicates, Athnasious Ghaly

Theses and Dissertations

For more than two decades, new innovative materials have been introduced to the market such as nano materials that can be utilized for their high performance in different aspects of the construction industry. Structural repair and strengthening is one of the most demanding fields in the construction industry for innovative and high-performance materials due to its specialty. Time, quality, economy, and sustainability are the main factors that control this field, and for that, new systems keep being introduced to the market to reduce the time of repair and enhance its efficiency. Fiber Reinforced Polymers (FRP) Systems are the most advanced …

A Study On High-Frequency Bending Fatigue, Microhardness, Tensile Strength, And Microstructure Of Parts Made Using Atomic Diffusion Additive Manufacturing (Adam) And Additive Friction Stir Deposition (Afsd), Hamed Ghadimi

LSU Doctoral Dissertations

This dissertation reports the findings of several studies on the mechanical and microstructural properties of parts made using atomic diffusion additive manufacturing (ADAM) and additive friction stir deposition (AFSD). The design of a small-sized bending-fatigue test specimen for an ultrasonic fatigue testing system is reported in Chapter 1. The design was optimized based on the finite element analysis and analytical solution. The stress–life (S–N) curve is obtained for Inconel alloy 718. Chapter 2 presents the findings of ultrasonic bending-fatigue and tensile tests carried out on the ADAM test specimens. The S-N curves were created in the very high-cycle fatigue regime. …

Mechanical And Electromagnetic Properties Of Incorporating Graphene Oxide In Cementitious Mixtures, Cherif Khalil

Theses and Dissertations

This multidisciplinary study aimed at investigating the impact of incorporating graphene oxide (GO) on the mechanical properties and electromagnetic (EM) shielding effectiveness of cementitious mixtures, as well as critically examining the mechanism with which GO affects their microstructure properties. Analysis of the literature review showed that there are discrepancies in reporting the impact of GO on the mortar mix. Consequently, this study focuses on exploring the cause for such discrepancies and identifies three main factors which are thoroughly investigated. The factors were the different sonication energies applied to the GO (Shear Mixing, 1.5 kJ/ml, 3 kJ/ml and 6 kJ/ml), the …

Balsa Bridge, Caleb T. Lovett

All Undergraduate Projects

The problem presented throughout this report was to create a small-scale bridge made entirely out of balsa wood and glue, that could withstand substantial force, as well as perform a lifting/lowering cycle. Other requirements associated with the bridge were properties of weight, deflection, size, and shape. This problem presented a challenge that tested the mathematical side of engineering, being strongly reliant on statics, mechanics of materials, and mechanical design analyses.

To approach this problem, the first step was to complete in depth calculations of the chosen design. With this done, manufacturing and assembly was able to be completed. With a …

Hempcrete Curtain Walls, Anh Bui

2024 Awards for Excellence in Student Research and Creative Activity - Documents

This research aims to scrutinize the performance, durability, and viability of hempcrete in curtain wall applications—an exploration critical to advancing sustainable construction practices. Comprising hemp hurds and lime binders, hempcrete stands as an emerging sustainable building material with promising ecological benefits. Despite its potential, there exists a notable research gap concerning its application in curtain walls, which demand rigorous structural and weatherproofing standards. The primary objective is to subject full-scale hempcrete curtain wall assemblies to ASTM standard test methods, comparing their performance with conventional materials like stone and glass. The research hypothesis posits that hempcrete will exhibit satisfactory strength, fire …

Predicting Compressive Strength Of Concrete Incorporating Fly Ash, Blast Furnace Slag, And Superplasticizer Using Machine Learning Techniques, Muhammad Faisal Yaqub

2024 REYES Proceedings

Concrete is the second most essential element in the construction industry, and its strength requirements vary based on the specific conditions of each project. However, determining the compressive strength of concrete involves laboratory tests, which wastes a lot of time and money. Researchers have developed machine learning models that predict the compressive strength of cement-based concrete having various mixes. In this research, the compressive strength of concrete incorporating fly ash, blast furnace slag, and superplasticizer is predicted using different machine learning models, namely, Linear Regression, Random Forest Regression, Decision Tree Regression, Extreme Gradient Boosting, Light Gradient Boosting, AdaBoost, and CatBoost …

Investigation Of Bone Structure And Composition Differences In Osteofibrous Dysplasia And Neurofibromatosis Type 1, Farzaneh Fereidouni

Material Science and Engineering Dissertations - Archive

Abstract

Investigation of Bone Structure and Composition Differences in Osteofibrous Dysplasia and Neurofibromatosis Type 1

Farzaneh Fereidouni, Ph.D.

The University of Texas at Arlington, 2024

Supervising Professor: Harry F. Tibbals

Bone genetic diseases such as Osteofibrous Dysplasia (OFD) and Neurofibromatosis type 1 (NF1) present significant challenges, particularly in children, due to their effects on skeletal homeostasis. This study aims to apply advanced material analysis to elucidate the biological disparities associated with OFD and NF1 bone dysplasia and contribute to developing diagnostic protocols and remediation approaches for these and similar bone disorders.

By employing various analytical methods, including analysis of mineral-to-matrix …

Kissing Bond Assessment In Adhesive Bonded Carbon Fiber Reinforced Composites Using Dielectric Spectroscopy, Minhazur Rahman

Mechanical and Aerospace Engineering Dissertations - Archive

The widespread use of fiber-reinforced composites in industries such as space, aviation, automobiles, and construction necessitates the formation of robust composite joints between critical structural components. Although adhesive-bonded joints are superior with improved load distribution and reduced weight, they are often overlooked in favor of bolted joints and mechanical fasteners due to the lack of reliable Non-Destructive Evaluation (NDE) techniques for adhesive-bonded composites. The anisotropic nature of the substrate and the intricate interfacial interactions between the adherend and adhesive material present significant challenges for conventional NDE methods. Moreover, weak adhesive bonds can result from uncontrolled manufacturing parameters, such as accidental …

Experimental Investigations And Optimization Of 3d Printed Cellular Structures For Protection Against Traumatic Brain Injury, Aaron R. Jackson

Mechanical and Aerospace Engineering Dissertations - Archive

Traumatic Brain Injury (TBI) disrupts brain function due to head impacts, blast exposures, and ballistic penetrations. It is a significant cause of mental health issues and disability, particularly among military personnel. Historically, combat helmets were designed primarily to protect against fragments. However, recent data highlights the need for helmets that also protect against blast and blunt impacts. Effective TBI prevention requires helmets that address various energy threats while remaining lightweight. A critical metric in this effort is head acceleration, which is closely linked to injury across different scales of brain damage.

Four lattice structures were 3D printed using Digital ABS …

Quantitative Modeling Of Micro Discharge And Oxide Growth In Plasma Electrolytic Oxidation Of Titanium, Kingsley I. Ochiabuto

Material Science and Engineering Dissertations - Archive

Plasma electrolytic oxidation (PEO) has been extensively applied in the past to improve the tribological properties of titanium and its alloys allowing their widespread use in industrial applications. However, the complete PEO mechanism of action remains unclear. While there are several mathematical models providing useful insights into the PEO process, they do not fully incorporate the effect of applied potential on the outcomes of PEO. In this work, we develop an experimentally informed computational model by expanding on the dielectric breakdown model. We incorporate experimental data to extract key parameters, exploring the iterative dependency of the oxide thickness and ionic …

Effects Of Hemp Fibers On The Mechanical Performance Of Concrete, Hamida Baassou

Masters Theses

The construction industry is known to be globally the number one contributor to greenhouse gas emissions (GHG) and energy consumption. The purpose of this study is to examine the potential use of hemp as a concrete reinforcement, its mechanical properties and strength, its environmental and socio-economic advantages, and its limitations. To examine the mechanical performance of hemp fiber, 54 specimens will be tested for compressive, tensile, and flexural strength. This was done in two parts. In the first part hemp fibers in two different ratios (0.5v% and 1v%), and two different treatments (water and 5% sodium hydroxide) were added to …

Advancing Combinatorial Screening Of Refractory High Entropy Alloys Through Intrinsic Ductility Assessment Via Thin Film Fragmentation Testing, Taohid Bin Nur Tuhser

Theses and Dissertations--Chemical and Materials Engineering

High Entropy Alloys (HEAs), also known as Multiprincipal Element Alloys (MPEAs), represent a paradigm shift in alloy design. Unlike traditional practices that limit compositions to the edges of phase diagrams, HEAs exploit equiatomic mixing of five or more elements at the center of phase diagrams to maximize configurational entropy. This unconventional approach exponentially expands the spectrum of potential alloy compositions, rendering conventional experimental methods inadequate for exploring this extensive compositional space.

In response to these challenges, the scientific community has shown a growing interest in high-throughput techniques, encompassing both computational and experimental domains. Particularly, Refractory High Entropy Alloys (RHEAs) have …

Microstructural Investigation Of The Influence Of Geometry On The Mechanical Reliability Of Additively Manufactured Metals, Tracy Connor Varney

Theses and Dissertations--Chemical and Materials Engineering

The adoption of additive manufacturing across a wide range of fields is ever-increasing, allowing for solutions that were previously impossible to achieve. This dissertation demonstrates the wide range of macro- and micro- characterization techniques used to investigate several precipitation strengthened AM alloy systems. While AM allows for nearly unlimited design freedom, this brings along its own issues as the interplay between scan strategy and part geometry is less well known. In this work, a novel thin-wall dogbone geometry was utilized to study one type of complex geometry observed in a large portion of AM focused designs. The mechanical behavior of …

Fatigue Resistant Cast Steel Railcar Couplers Produced By Wire-Arc Additive Manufacturing (Waam), Samuel Vellequette

Dissertations, Master's Theses and Master's Reports

Every year, approximately 90,000 cast steel railcar coupler knuckles are replaced preemptively to avoid fatigue failure. The coupler geometry has been in service since the early 1930s, so geometry changes are restricted to maintain compatibility with the existing fleet. Defects from the casting process, decarburization during heat treatment, and in-service exposure to corrosive environments combine to promote fatigue crack nucleation in high-stress regions of the knuckle. Wire-arc additive manufacturing (WAAM), which uses traditional welding techniques to build material to near-net shapes, was employed to deposit higher-strength materials in critical regions. By replacing the cast steel in the high-stress region of …

Degree Of Dispersion/Exfoliation And Surface Functionalization Of 1d And 2d Carbon Nanostructured Materials: Interface Interactions And Effects On Mechanical Properties, Michail Margas

Material Science and Engineering Dissertations - Archive

The development of advanced cementitious nanocomposites relies heavily on understanding the interfacial interactions between carbon-based nanomaterials and the cement matrix, which significantly influence the material’s performance. The goal of this dissertation is to investigate the effect of dispersion/exfoliation and surface functionalization of 1D multiwall carbon nanotubes (MWCNTs), carbon nanofibers (CNFs), and 2D graphene nanoplatelets (GNPs) in aqueous suspensions on the interface interactions of nanoengineered cementitious composites. The first objective of this dissertation is to quantitatively evaluate the degree of nanomaterial dispersion for MWCNT and CNF suspensions, in a converging manner for cement-based materials applications using spectroscopic techniques, such as UV-vis …

Molecular Modeling Of Phenolic Resin For Carbon-Carbon Composites, Ivan Gallegos

Dissertations, Master's Theses and Master's Reports

One of the most difficult challenges associated with space exploration is terrestrial atmospheric reentry due to the high thermal loads generated. Carbon carbon (C/C) composites have been used as heat shielding materials due to their high strengthto- weight ratio and thermal properties and their applications include heat shielding for various high temperature environments. C/C composites are manufactured by polymer-infiltration pyrolysis (PIP) via cycles of curing and pyrolysis of a prepreg which can be costly and take up to several days. Thus, C/C composites ideal candidates for computationally-driven optimization techniques, such as a multiscale Integrated Computational Materials Engineering (ICME) approach, by …

Extending Trailer, Alex Grove

Williams Honors College, Honors Research Projects

The goal of this research project is to revolutionize the convenience in towable transportation. This innovative design aims to enhance the versatility of pull-behind trailers by incorporating an extendable feature, allowing users to effortlessly adjust the length according to their specific needs. Whether navigating tight spaces or accommodating extra cargo, our trailer adapts to diverse situations, providing unmatched flexibility. In addition to its adjustable length, the trailer is engineered to be compactable, addressing the storage constraints often faced by users with limited space. The collapsible design ensures easy storage without compromising on functionality, making it an ideal solution for individuals …

Novel Precursors For Carbon Fiber Prepared By Direct Carbonization, Leah Noble

Theses and Dissertations--Chemical and Materials Engineering

For decades carbon fiber-based composites have been most heavily employed in lightweight, structural applications where low density and high strength are necessary, most notably within the aerospace industry. However, the advancement of carbon fiber into a wider array of industries has largely been limited by the high financial and energetic costs associated with its manufacture. Moreover, with an increasing societal emphasis on sustainability, there is an ever-growing desire for low-energy carbon fiber production pathways. One such pathway is the conversion of precursor fiber to carbon fiber by direct carbonization, wherein the energy-intensive, pre-carbonization stabilization step is omitted from the carbonization …

Experimental Investigation Of Liquid Metal Embrittlement In Hot-Dip Galvanized Structural Steel, Amelia Mcnamee

College of Graduate Studies: Theses & Dissertations

This research investigated the liquid metal embrittlement (LME) of hot-dipped galvanized structural steel. The relationship between stress and failure time was analyzed to evaluate the potential presence of a critical stress threshold beyond which LME may occur. A testing apparatus to induce axial stress was designed and assembled in-house. A36 low carbon steel was tested in this study. Different deadweight loadings were applied to the testing sample along the axial direction. The test temperature was maintained by a programmable furnace while the sample gauge section was submerged in a molten zinc bath. Failure time and total displacement of the steel …

Impact Of Quenching Intensity Conditions On Using A Finite Element Model To Investigate The Microstructure And Hardenability Of Low-Alloy Steel, J. S. Alabi, E. Heidari, M. F. Buchely, K. Chandrashekhara, S. N. Lekakh, R. J. O'Malley, V. Athavale, A. Kumar

Materials Science and Engineering Faculty Research & Creative Works

Quenching is one of the primary processes to improve mechanical properties in steels, particularly hardness. Quenching is well established for different geometries of individually treated steel components; while in-steam quenching of large diameter continuously cast steel bar has several specific features which are difficult and costly to experimentally optimize. the end-quench Jominy test has been used extensively to study the hardenability of different steel grades. Different numerical, analytical, and empirical models have been developed to simulate the Jominy process and to understand quenching of steels. However, it is not straight forward to translate experimental data from Jominy test on instream …

Impact Of Quenching Intensity Conditions On Using A Finite Element Model To Investigate The Microstructure And Hardenability Of Low-Alloy Steel, J. S. Alabi, E. Heidari, M. F. Buchely, K. Chandrashekhara, S. N. Lekakh, R. J. O'Malley, V. Athavale, A. Kumar

Materials Science and Engineering Faculty Research & Creative Works

Quenching is one of the primary processes to improve mechanical properties in steels, particularly hardness. Quenching is well established for different geometries of individually treated steel components; while in-steam quenching of large diameter continuously cast steel bar has several specific features which are difficult and costly to experimentally optimize. The end-quench Jominy test has been used extensively to study the hardenability of different steel grades. Different numerical, analytical, and empirical models have been developed to simulate the Jominy process and to understand quenching of steels. However, it is not straight forward to translate experimental data from Jominy test on instream …

Machine Learning-Assisted Multiscale Simulation And Design Optimization Of Composite Jackets Under Low-Velocity Impacts, Masoud Mohammadi

Graduate Theses, Dissertations, and Problem Reports (ETD)

This research presents the development of a data-driven machine learning-assisted approach to simulate and optimize the design of composite materials subjected to low-velocity impacts. It focuses on a specific type of hybrid composite comprised of fiberglass and Kevlar fabrics stitched with Kevlar threads. The study begins by creating a multiscale finite element simulation for the composite under a low-velocity impact, which operates across three scales: microscale, mesoscale, and macroscale. This simulation accepts various inputs, such as different layer configurations and orientations, and provides impact outputs including maximum load and energy absorption capacity and displacement at failure.

Python and MATLAB scripts …